In the new scientific volume Biological Information: New Perspectives (BINP), mathematician Granville Sewell of the University of Texas, El Paso, has an article titled "Entropy, Evolution and Open Systems," where he argues that the second law of thermodynamics could potentially pose a barrier to Darwinian evolution. He recently published a similar paper in BIO-Complexity, "Entropy and Evolution," where he presents his case in more detail. In this pair of articles, Sewell argues not that the second law of thermodynamics necessarily poses a barrier to Darwinian evolution, but rather that it could pose a problem, provided that the issue is framed properly. As I've explained before, this is very different from old, unsophisticated and flawed arguments you may have heard about the second law and evolution.

Fixing a Flawed Argument

In the past, critics would argue that Darwinian evolution necessarily violates the second law of thermodynamics because the law predicts that entropy (a measure of disorder) will increase, yet Darwinian evolution purports to decrease disorder over time. This argument had major problems. Defenders of Darwinism would reply by pointing out that the second law merely holds that "entropy tends to increase in a closed system," and since the Earth is an open system, constantly receiving energy from the sun, the second law doesn't prohibit entropy from decreasing on our planet.

Sewell's recent articles address the rejoinder from Darwin-defenders and reframe the issue to show that the second law could potentially be a problem for Darwinian evolution. In his BINP paper, he observes that we have no experience with sunlight producing the kind of order and complexity needed for life:

Thus unless we are willing to argue that the influx of solar energy into the Earth makes the appearance of spaceships, computers and the Internet not extremely improbable, we have to conclude that at least the basic principle behind the second law has in fact been violated here.

The argument from Darwin-defenders is that if entropy increases elsewhere in the universe, then it can decrease in open systems such as the Earth. Sewell calls this the "compensation" argument, and explains why it is seriously flawed:

It is widely argued that the spectacular local decreases in entropy that occurred on Earth as a result of the origin and evolution of life and the development of human intelligence are not inconsistent with the second law of thermodynamics, because the Earth is an open system and entropy can decrease in an open system, provided the decrease is compensated by entropy increases outside the system. I refer to this as the compensation argument, and I argue that it is without logical merit, amounting to little more than an attempt to avoid the extraordinary probabilistic difficulties posed by the assertion that life has originated and evolved by spontaneous processes. To claim that what has happened on Earth does not violate the fundamental natural principle behind the second law, one must instead make a more direct and difficult argument.

Sewell elaborates that "the compensation argument is predicated on the idea that there is no content to the second law apart from a prohibition of net entropy decreases in isolated systems, and moreover that the universal currency for entropy is thermal entropy." In his BINP paper, he explains:

Of course the whole idea of compensation, whether by distant or nearby events, makes no sense logically: an extremely improbable event is not rendered less improbable simply by the occurrence of "compensating" events elsewhere. According to this reasoning, the second law does not prevent scrap metal from reorganizing itself into a computer in one room, as long as two computers in the next room are rusting into scrap metal -- and the door is open. (Or the thermal entropy in the next room is increasing, though I am not sure how fast it has to increase to compensate for computer construction!)

In the BINP volume, he sums up as follows:

The second law of thermodynamics is all about probability; it uses probability at the microscopic level to predict macroscopic change. Carbon distributes itself more and more uniformly in an isolated solid because that is what the laws of probability predict when diffusion alone is operative. Thus the second law predicts that natural (unintelligent) causes will not do macroscopically describable things which are extremely improbable from the microscopic point of view. The reason natural forces can turn a computer or a spaceship into rubble and not vice versa is probability: of all the possible arrangements atoms could take, only a very small percentage could add, subtract, multiply and divide real numbers, or fly astronauts to the moon and back safely.

Sewell concludes "The 'compensation' counter-argument was produced by people who generalized the model equation for isolated systems, but forgot to generalize the equation for non-isolated systems." His generalized model would be as follows: "If an increase in order is extremely improbable when a system is closed, it is still extremely improbable when the system is open, unless something is entering which makes it not extremely improbable."

Again, Sewell's argument is not that the second law is necessarily a barrier to Darwinian evolution since, "Of course, one can still argue that the spectacular increase in order seen on Earth is consistent with the underlying principle behind the second law because what has happened here is not really extremely improbable...But one would think that at least this would be considered an open question, and those who argue that it really is extremely improbable, and thus contrary to the basic principle underlying the second law of thermodynamics, would be given a measure of respect, and taken seriously by their colleagues."

A New BIO-Complexity Paper: A Further Defense of Sewell's Argument

Sewell's BIO-Complexity paper is worth exploring further because it contains lots of unique material, including a response to Bob Lloyd, his critic in The Mathematical Intelligencer in 2012. This response requires a bit of background.

So Sewell is the victim of double-censorship: he isn't allowed to publish his ideas in a journal, and then when his ideas are attacked in another journal, he's not allowed to publish his rebuttal there either. If Sewell's AML paper was so bad that it didn't deserve to be published, why do his critics feel the need to rebut it?

Now, Sewell has been given his opportunity to respond to Lloyd with a technical paper in BIO-Complexity.

Lloyd had argued:

[A]lthough there is a local decrease in entropy associated with the appearance and evolution of life on Earth, this is very small in comparison with the very large entropy increase associated with the solar input to Earth. This qualitative idea has received quantitative backing from the calculations of Styer, and particularly as modified by Bunn, which show that the solar contribution is many orders of magnitude larger than any possible decrease associated with evolution.

In BIO-Complexity, Sewell replies by asking us to consider four "test scenarios":

A. In an isolated steel object, the temperature distribution is initially non-uniform, and becomes more uniform with time, until the temperature is constant throughout. Then, the temperature distribution starts to become non-uniform again.

B. In an isolated steel object, the chromium distribution is initially non-uniform, and becomes more uniform with time, until the chromium concentration is constant throughout. Then, the chromium distribution starts to become non-uniform again. (In this scenario, you can replace chromium by anything else that diffuses, of course, and we are assuming nothing is going on but diffusion.)

C. A tornado hits a town, turning houses and cars into rubble. Then, another tornado hits, and turns the rubble back into houses and cars.

D. The atoms on a barren planet spontaneously rearrange themselves, with the help of solar energy and under the direction of four unintelligent forces of physics alone, into humans, cars, high-speed computers, libraries full of science texts and encyclopedias, TV sets, airplanes and spaceships. Then, the sun explodes into a supernova, and, with the help of solar energy, all of these things turn back into dust.

Sewell explains that scenarios A and B generate little controversy. In each, the second law is obeyed during the first phase, and violated during the second phase.

The compensation argument is widely used to claim that the first phase of scenario D does not violate the second law, but it could equally well be used to claim that the second tornado of scenario C, which turns rubble into houses and cars, would not violate the second law either. As Sewell puts it, "In other words, the compensation argument can be used to justify scenarios that all scientists would recognize to be entropically implausible, and this means that it does a poor job of representing the actual content of the second law." He responds to one Darwinian evolutionist who uses this argument by stating: "In other words, using Styer's understanding of entropy, the fact that evolution is astronomically improbable is not a problem as long as something (anything, apparently) is happening elsewhere which, if reversed, would be even more improbable."

Sewell shows that all of the arguments commonly employed to claim that evolution did not violate at least the underlying principle behind the second law, could equally well be applied to claim that tornados turning rubble into houses and cars would not violate it either. This is, of course, absurd.

Sewell thus shows that, given the second law of thermodynamics, the compensation argument does not necessarily solve the problem for Darwinian evolution. If Darwinian advocates were willing to candidly examine the improbabilities faced by their theory, they would see that a serious question -- among many others, of course -- remains to be answered.